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Horn Question

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bugedd

bugedd

Jedi Knight
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Two years ago, when I got my car, I ran a new wiring harness. The car didn't have a horn, so I left the connectors taped off. Finally I am getting around to putting a horn in, and wanted to see if the horn button was working properly before I tighten all the bolts down. With the ignition on or off, I am reading a bit over 9V at the horn wires. When the horn push is depressed, nothing happens. I have a Motolita steering wheel/horn push. Can someone give me some direction on where I need to go with this? I would think that I should only have hot there when the ignition is on, but perhaps not. And I would think that it should be dead at the wires until I depress the horn push.
Thanks for the guidance.
 
First, the horns always hot, second, there's a circular disc behind the horn push and pencil like device with a spring at the end with the live wire...If you don't have all these in working order no noise!
 
I do have those parts. Is it supposed to ground it and that sounds the horn?
 
The horn wire which connects to the disc and spring loaded contact is grounded to the steering column when pushed. Just to rephrase, the 12V goes to the horns up front, then the return goes to the disc, spring loaded contact and the horn button. What frequently happens, is the steering column is not chassis ground, but is insulated by the steering rack. For my build, I had to run a wire from the steering rack to ground in order to get a reliable horn. An easy way to check is to see if the steering column is connected to battery ground.
scott in CA.
 
All the above is correct but you have yet another problem too if you only get 9 volts at the horn wire. That probably is not enough to activate the horn.
 
Bayless said:
All the above is correct but you have yet another problem too if you only get 9 volts at the horn wire. That probably is not enough to activate the horn.
Click to expand...

But it is plenty to activate a relay - this would be a good use for one - particularly if it is original wiring.
 
what reading should I get at the horn wires when the horn is depressed?
As it is, with the car off its 9-10V when testing the two wires.
 
I typically mechanical relay might not be the absolute best for this application. A transistor might be a better option (because of the speed of switching).

And this guy will show you how to do it if you are interested..

https://www.nonlintec.com/sprite/horn/

(although you can use a mechanical relay, you just might not always get a quick beep if you just quickly hit the horn..)
 
If you are only getting 9-10V at the "hot" side of the wiring for the horn, something isn't right. You should see the full battery voltage. It's likely that something isn't connected right.

BTW that's my write-up about the electronic relay. But, get the horn working normally before trying this. If it isn't wired right, the electronic relay won't work any better than the stock system.
 
Wouldn't getting an aftermarket air horn accomplish the same as wiring up a relay? Don't they have an integrated relay? From what I hear, the stock horns are pretty weak anyhow, so might as well go big!

So now the question would be, why the voltage drop? The system is darn simple, can't see how anything can be connected wrong.
 
the original wiring for the BE horns has the hot wire attached to one of the two fuse connections (only thing connected). It is not uncommon for the connections on the back side to get loose, and not make good contact. Trace with your voltmeter back from the horns to the horn side of the fuse box, then to the battery side of the fuse box (note horn is hot all the time, blows without the key being on). In all cases you should see battery voltage of 12v. Check the battery first, with the voltmeter grounded well, and then move the + probe around to various locations.
To check if the horns will blow, just ground the wire that leads up to the instrument panel from the horns, not the hot one, but the other one.
checking electrical stuff is like seeing if a pipe has water pressure. Start at the source (battery) and then follow it downstream (fuse box + side), fuse box (horn side), at the horns.
Hope that helps
Scott in CA
 
So I think my wiring is fine, now to get a horn. Now, what are the opinions of horns to purchase that are plug-n-play. Meaning now relays, jumper wires, blah, blah. I can't find anything out there that fits that, in Moss or Victoria. Is there someone that rebuilds originals and does not charge and arm and a leg?
 
Bugedd, I sent mine to a guy named Lawrie Rhodes at <span style="text-decoration: underline">British Car Part Restoration</span>s. .

I can't remember what it cost, more than a generic horn, for sure. I think it costs out okay IF you already have the original in hand. If you had to purchase an original and it wasn't working you would definitely deeply underwater cost-wise by the time you were done having it restored.

Even repaired the tone of the original is rather anemic, although it is cool to have the horn that came with the car operable there are times I wish I had gone with a newer one.

Good luck
Charlie
 
Have you tried doing an adjustment on the horns? Mine sounded rather blah initially but after I adjusted them they were a lot better. Just loosen the big nut on the body and play around with the screw and you can can make a big difference in the sound. Now I have retired them anyway and have installed the monstrously loud air horn from Griot's Garage. Bill L. put me onto it after he described having it on his car.
 
Nelson said:
Have you tried doing an adjustment on the horns? Mine sounded rather blah initially but after I adjusted them they were a lot better. Just loosen the big nut on the body and play around with the screw and you can can make a big difference in the sound. Now I have retired them anyway and have installed the monstrously loud air horn from Griot's Garage. Bill L. put me onto it after he described having it on his car.
Click to expand...

I haven't done it yet but will shortly be putting the loudest horns I can find in Ms Triss. Got "bumped" last year - no damage and I doubt a horn would have changed anything (parking lot) but want every advantage on my side.
 
Installing a relay is easy, and only requires adding ONE more wire. I can understand NOT wanting to go thru all that and just having a stock horn, but the time-cost/reward ratio so far as installing-buying/loudness is well worth it. It also takes the load off the stock horn circuit and horn push making it more reliable/longer lasting.

YMMV
NFI
IMHO
etc.
 
I was looking at Hella horns yesterday, a high and a low tone, with relay. The stock wires are brown/black (ground) and brown/green (hot 12V). The horns show 12V to relay, then from relay to horns, 2 hots, and then grounding each horn to chassis bolt or where ever.
Now, with the relay, would I jut run the brown/green to the relay? And what do I do with the brown/black? To the relay as well? And I thought the circuit worked on grounding at the horn push, so if each horn is grounded, will it still work?
 
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